Can bees meet their nutritional needs in the current UK landscape?

An important but often overlooked reason that bee populations are in decline is likely to be that these important pollinators can no longer obtain adequate nutrition as a result of changes in land management practices worldwide. This proposal will investigate how honeybees and bumblebees meet their nutritional needs and will also examine the nutritional value of pollen and nectar of selected UK plant species with the aim of predicting when bee pollinators in the UK experience nutritional short-falls. Insects, and in particular bee species, are responsible for the sexual reproduction of a highly diverse range of plants, many of which are agricultural crops. Over 39 crops in the UK alone depend upon insect pollinators for fruit and seed production. In natural habitats, a colony of 'generalist' bees such as honeybees will visit the flowers of potentially hundreds of different plant species to find food. In the past 50 years, our landscape has changed to accommodate modern farming practices that cultivate large fields of single crop species. Nutritional balance becomes extremely important in monoculture situations: honeybee colonies used for pollination services have little or no choice of food and limited access to natural vegetation.. Ironically, while crops like oilseed rape may provide vast expanses of pollen and nectar when they are in flower, we do not know if these floral resources provide adequate nutrition for bees. In fact, species like honeybees may be obliged to forage for pollen and nectar from a variety of plants to obtain adequate nutrition, but this has never been established. Using a sophisticated modelling approach that has been developed to study nutrition in many other animals, we will experimentally determine the ratio of protein and carbohydrates that adult workers and larval bees need to perform at their best. We will also examine how changes in environmental conditions, infection with pathogens, exposure to pesticides, or consumption of toxins affect a bee's nutritional needs. Honeybees and bumblebees learn to associate floral traits with food and so can exploit flowers that are currently in bloom. By placing bees under circumstances where they are forced to eat unbalanced foods, we will test whether malnourishment causes bees to learn to select foods that complete their diet. Honeybees are social insects that communicate information about floral resources to other workers within the hive via the 'dance language' in order to rapidly exploit available food sources. We will also examine whether nutritional imbalance causes bees to dance more vigorously for nutritionally complete foods. An important component of our proposed research will use a series of biochemical analyses to determine the nutritional value of pollen and nectar of important bee-pollinated plants. We will focus our investigation on important UK crops (e.g. oilseed rape, apples, peas), plants found in natural UK landscapes including invasive species (e.g. clover, heather, Himalayan balsalm), and plants found in urban gardens (e.g. mint, rhododendrons, cucumbers). Combining this information with a careful analysis of the existing scientific literature, we will construct an online database of the nutritional value of pollen and nectar of flowering plants in order to share this information with the general public. When combined with the experiments that determine optimal bee nutrition, we anticipate that the research described in our proposal will aid beekeepers, farmers, land managers, and scientists in thwarting bee decline worldwide, by providing a sound scientific basis for designing strategies to ensure that bees have access to sufficient nutrients.

During the last 50 years, plant diversity in the UK has been reduced in some areas by as much as 75%. An important but often overlooked factor that could be playing a leading role in bee population declines is the fact that bees may not have access to sufficient nutrition from existing floral resources. Nutrition is vitally important for animals: poor nutrition has direct fitness consequences including increased susceptibility to parasites and pathogens, fewer resources for rearing offspring, and a reduced ability to thermoregulate or metabolise ingested toxins. We know surprisingly little about the nutritional needs of bees or how these needs are met by foraging on nectar and pollen. The research proposed here will be the first to use the nutritional models of Simpson and Raubenheimer (1993) to determine the protein-to-carbohydrate ratios (intake targets) of adult foragers and larvae of honeybees (Apis mellifera) and bumblebees (Bombus terrestris). We will examine in detail the conditions under which intake targets change, such as infection with pathogens, exposure to pesticides, changes in temperature, or increased demands of brood. We will also examine how nutritional imbalance affects foraging decisions, by testing whether bees are more likely to learn and remember floral traits associated with nutrients that complete their diets. We will also examine how nutritional imbalance affects the dance language of bees, predicting that bees will dance more vigorously for food sources that complete their diet. An important facet of this research will also be the biochemical analysis of protein, amino acids, carbohydrates, fatty acids, and toxins found in pollen and nectar from important crops, as well as native, invasive, and horticultural plant species in the UK landscape. These data will be incorporated into an online database that will also include a meta-analysis of the existing literature on the nutritional qualities of pollen and nectar.

The output from research described will have a positive long-term impact on agricultural crop production and beekeeping while advancing our understanding of why pollinators are currently in worldwide decline. Much of the world's food production comes from plants which depend on pollinators for out-crossing and fertilization. Understanding whether or not bees can meet their nutritional needs by feeding on the nectar and pollen provided by crop plants will allow beekeepers and farmers to predict when pollinators are likely to experience nutritional shortfalls. When crops do not provide sufficient sources of nutrition, our research will equip beekeepers with the knowledge needed to provide the appropriate nutritional supplements to maintain bee health. Our research will also provide information valuable for developing an artificial honeybee diet for periods when colonies are building during brood rearing or in preparation for commercial pollination or over-wintering. Thus, the data we generate are likely to have a large and lasting impact on this industry and on crop pollination worldwide. We also expect that industries servicing the beekeeping industry that make food supplements (e.g. FeedBee) will greatly benefit from knowing the intake targets of bees and the nutritional value of floral resources. For example, pollen is often used as a supplemental food; determining the nutritional value of several types of pollen would allow companies which sell pollen supplements to use pollen types which provide the best nutritional value instead of a common mix of pollen from many plant species. For the same reasons, we also anticipate that our research will have an impact on bumblebee husbandry for pollination services. Our research also has important implications for determining the impacts of other factors on bee decline, such as diseases and pesticides. We anticipate that future studies conducted by our group and by other international groups of scientists will further test the importance of nutritional imbalance in bee susceptibility to diseases, parasites, and toxicity caused by exposure to pesticides. Furthermore, an important and long-lasting outcome of our research will be the information about the necessity for plant diversity in providing adequate floral resources for wild bee populations. We expect that compiling information about pollen and nectar quality of naturally-occurring UK plant species will aid those engaged in wild bee conservation and land-management strategies by allowing them to foster habitats with complementary floral resources for bees. Our research, therefore, could potentially impact policies aimed at issues as diverse as the control of invasive plant species and the improvement of plant diversity in land bordering urban and agricultural areas. The general public has a keen interest in bees, as demonstrated by the response to the publication of the government's support for the Insect Pollinators Initiative. Some of the main beneficiaries of our research will be the general public via educational outreach. Using existing resources at our respective institutions of Moorbank Botanic Garden at Newcastle University and the Royal Botanic Gardens at Kew, we expect to develop several initiatives aimed inspiring interest in the way that pollinators obtain nutrition from flowering plants. This includes approaches to public engagement from involving primary school children in projects to developing visual displays such as observation hives and 'bee gardens' within the gardens which visitors can access.